Efficient allocation of network resources, such as available network bandwidth, has become critical as enterprises increase reliance on distributed computing environments and wide area computer networks to accomplish critical tasks. The widely-used TCP/IP protocol suite, which implements the world-wide data communications network environment called the Internet and is employed in many local area networks, omits any explicit supervisory function over the rate of data transport over the various devices that comprise the network. While there are certain perceived advantages, this characteristic has the consequence of juxtaposing very high-speed packets and very low-speed packets in potential conflict and produces certain inefficiencies. Certain loading conditions degrade performance of networked applications and can even cause instabilities which could lead to overloads that could stop data transfer temporarily. The above-identified U.S. Patents and patent applications provide explanations of certain technical aspects of a packet based telecommunications network environment, such as Internet/Intranet technology based largely on the TCP/IP protocol suite, and describe the deployment of bandwidth management solutions to monitor and manage network environments using such protocols and technologies.
FIG. 1 illustrates a computer network environment including a bandwidth management device 130 deployed to manage network traffic traversing a single access link 21 connected to a open computer network 50, such as the Internet. With the increasing use and reliance on networks in business to accomplish daily tasks, efficiency, performance and reliability are key features of enterprise networks. For example, an important aspect of implementing enterprise-grade network environments is provisioning mechanisms that address or adjust to the failure of systems associated with or connected to the network environment, such as routers, switches and bandwidth management devices. Accordingly, many enterprise network architectures feature redundant topologies to provide for load balancing to maintain efficiency and performance, and fall-over support for reliability. For example, as FIG. 2A illustrates a typical enterprise network infrastructure may include a plurality of access links (e.g., 21a, 21b) connecting an enterprise LAN or WAN to an open computer network 50. In these network topologies, network traffic may be directed completely through one route or may be load-shared between alternative routes. FIG. 2B provides another redundant network topology where first and second routers 22a, 22b are connected to corresponding access links 21a, 21b and to a single bandwidth management device 30 via switches 23. In addition, FIG. 2C shows a redundant network topology similar to that shown in FIG. 2B; however, not all network traffic traversing the access links 21a, 21b encounters bandwidth management device 30. Still further, FIG. 2D illustrates a redundant network topology including redundant bandwidth management devices 230a, 230b configured with network traffic synchronization functionality, as disclosed in U.S. application Ser. No. 10/611,573. Of course, a wide variety of deployment scenarios and configurations are possible. Network devices, such as bandwidth management devices, that perform some network function must be configured to effectively respond to the behavioral characteristics associated with these increasingly complex network topologies.
According to the deployment scenario illustrated in FIG. 2A, bandwidth management device 30 manages network traffic traversing access links 21a, 21b in both the inbound (from network 50 to LAN 40) and outbound (from LAN 40 to network 50) directions. In the outbound direction, for example, bandwidth management device 30 emits network traffic to router 22, which routes and/or load balances the network traffic across access links 21a, 21b. For purposes of various rate control and bandwidth management computations (e.g., partitions, rate policies, minimum bandwidth guarantees, etc.), bandwidth management device 30 effectively treats access links 21a, 21b as one virtual link, whose size or capacity is the sum of the capacities of each access link 21a, 21b. Accordingly, if the maximum bandwidth of each access link was 50 Kbps, for example, the virtual link size would be 100 Kbps. This model further assumes that router 22 evenly distributes network traffic across access links 21a, 21b. This assumption-based model of the router's 22 behavior is also made in the other deployment scenarios illustrated in FIGS. 2B, 2C and 2D.
As to the deployment scenarios described above, however, this model of routing behavior often does not correctly characterize the manner in which a routing system, such as router 22 in FIG. 2A, routes and/or load balances traffic across multiple access links, such as 21a, 21b. For example, a routing system chooses a given access link based on considerations, such as best path to the destination host, in addition to load or other considerations. Accordingly, this often results in an uneven distribution of network traffic across access links 21a, 21b. This circumstance renders control of network traffic on a network-wide basis problematic, and without the present invention, may result in one or more access links or routers associated with a given access link becoming overloaded, reducing network efficiency resulting from retransmission of lost or dropped packets. For example, assume for didactic purposes that bandwidth management device 30 currently emits outbound network traffic (i.e., data flows sourced from local area network 40) at a rate of 55 Kbps, and that the network traffic load emitted from the router interface associated with access link 21a is 30 Kbps, while the network traffic emitted from the router interface associated with access link 21b is 25 Kbps. If the actual capacity of each access link is 40 Kbps, an assumption that the virtual link capacity is 80 Kbps may result in an overload condition for access link 21a, assuming that an increase in network traffic emitted from bandwidth management device is distributed consistently with the current ratio of 6:5. In fact, access link 21a will most likely become overloaded before the theoretical capacity of 80 Kbps is ever reached. Still further, the load at any given access link, as well as the distribution of network traffic across the access links, varies over time; therefore, the virtual link capacities computed by bandwidth management device 30 should preferably be dynamically adjusted depending on the current loading conditions observed on the network.
Furthermore, additional considerations are also present in the network topology illustrated in FIG. 2C, which includes a first network 140 and a second network 240, such as Demilitarized Zone (DMZ) comprising a plurality of web servers 44. In this network topology, second network 240 is essentially an additional source of network traffic (and, therefore, consumer of available bandwidth across access links 21a, 21b). Bandwidth management device 30, however, does not see the network traffic sourced from, or destined for, the second network 240 and, therefore, has no ability to account for it. This circumstance also breaks an additional assumption on which the virtual link capacity is derived according to prior art methodologies—namely, that the bandwidth management device, either individually or collectively with other devices, encounters all inbound and outbound network traffic.
In light of the foregoing, a need in the art exists for methods, apparatuses, and systems that allow bandwidth management and other network traffic control devices to adjust to respond to actually loading conditions across the network infrastructure. Embodiments of the present invention substantially fulfill these needs.